Allan Sandfeld Jensen wrote: >>Yes. I still don't understand why gcc doesn't do -ffast-math by >>default like all other compilers.
Vincent Lefevre wrote: > No! And I really don't think that other compilers do that. > It would be very bad, would not conform to the C standard[*] > and would make lots of codes fail. Perhaps what needs to be changed is the definition of -ffast-math itself. Some people (myself included) view it from the standpoint of using the full capabilities of our processors' hardware intrinsics; however, -ffast-math *also* implies the rearrangement of code that violates Standard behavior. Thus it does two things that perhaps should not be combined. To be more pointed, it is -funsafe-math-optimizations (implied by -ffast-math) that is in need of adjustment. May I be so bold as to suggest that -funsafe-math-optimizations be reduced in scope to perform exactly what it's name implies: transformations that may slightly alter the meanding of code. Then move the use of hardware intrinsics to a new -fhardware-math switch. Does anyone object if I experiment a bit with this modification? Or am I completely wrong in my understanding? ..Scott
